In the treatment of the wastewater, the Cedar Rapids Water Pollution Control Facilities (CRWPCF) generates solid material that is either incinerated or land applied as fertilizer and soil conditioner. When the solids are to be land applied CRWPCF adds lime to the material to raise the pH. The material is now called "biosolids" and undergoes laboratory testing for nutrient and metals content, presence of pathogens and continued pH checks. The land application of biosolids are regulated by the Iowa Department of Natural Resources and Environmental Protection Agency. If the biosolids meet the criteria set by these agencies, the biosolids are land applied to agricultural fields in the area.
